1. Field Of The Invention
This invention relates generally to a control system for a traffic light, and more particularly to a traffic light control system for enabling drivers to anticipate a change in a traffic signal from green to red so that they can properly adjust their speed for fuel conservation and safety purposes.
2. Description Of The Prior Art
Traffic control signaling devices are used at busy stree tand road intersections and are commonly employed to incorporate Stop and Go signals, These signals are electrically operated from a control box adjacent the traffic control signaling devices or adjacent a group or set of such devices. For predetermined periods or cycles of time, the Go and Stop signals, commonly respectively, colored green and red, are alternately displayed relative to a certain path of traffic movement. In this manner, while the green signals are giving the right of way to traffic headed in either of the two directions in which such signals face, the red signals are displayed to arrest traffic which otherwise would travel in the two directions faced by the red signals and which intersect the two former directions.
Early in the development of such traffic signaling devices, a third signal was added. This signal was amber or yellow to signify caution. Following the termination of each giving of red and green signals relative to traffic at a road or street intersection and before reversal of the signals to change the directions of traffic flow, the caution signal was displayed. Practice apparently proved, however, that the use of such caution signals was not entirely advantageous. In the early signaling devices using only red and green signals, the change-over from a Go to a Stop indication, and vice versa, was abrupt and sudden and of considerable inconvenience and even hazardous to pedestrians and drivers alike.
Since considerable difficulty was experienced by motorists in bringing their automobiles to a stop when a green light suddenly changed to red, the amber caution light was included, but this does not, by any means, represent a full solution to the problem, since the amber or yellow caution light remains on, usually, for only a very few seconds. Thus, the motorist may be approaching an intersection, maintaining a normal rate of speed sufficient in his or her judgement, to permit the driver to pass the intersection while he orshe still has a green light, and may be suddenly confronted with an imminent light change when he or she is almost at the intersection. Under these circumstances, it is necessary that the driver either bring the vehicle to a sharp or sudden stop, or alternately, continue on through the intersection despite the fact that the signal may be completely changed before he or she is fully through the intersection.
It will be seen from the above that it is highly desirable that the motorist be provided with a visual indication, from the time the signal changes until the next change thereof, that will provide him or her with full knowledge as to the amount of time remaining before the next signal change. In this way, the driver can prepare himself or herself further in advance, either for bringing the vehicle to a halt at the intersection, or alternatively, for preparing the vehicle to leave the intersection after it has been stopped thereat by a red stop light.
It has been heretofore proposed to provide a visual indication on a traffic light signal whereby one can determine, generally, the extent of time remaining before the next light change. Furthermore, systems have been devised which provide an improved type of device which is particularly adapted to provide a visual indication that can be seen at a substantial distance so that an oncoming motorist can readily perceive the extent of time in the signal cycle which remains before he or she reaches the intersection, and so that pedestrians can perceive the extent of time remaining in the signal cycle until they can cross safely through the intersection or during which they must wait before they can safely cross.
Many of the systems proposed by the prior art involve significant modifications too the hardward of the traffic signals themselves and significant changes in the control units therefore. This has proved too expensive to install, too difficult to maintain, and often to confusing to use safely.
It is desirable that the proposed changes to the traffic light control systems do not involve any significant amount of modification of the existing traffic control equipment, circuitry, or hardware. Systems have attempted to solve this problem more recently by blinking the green light near the end of its cycle before the amber light comes on and by blinking the red light at the end of its cycle before it reverts to green. Such signals are often confusing, and both drivers and pedestrians are not materially assisted in making safe decisions.
None of the systems of the prior art provide an extremely simple, yet relatively full-proof, method and apparatus for enabling a driver to anticipate a change in the traffic signal from green to red in sufficient time to safely judge whether or not to stop or proceed through the intersection. Applicant's invention solves relatively all of these prior art problems by providing a simple, low-cost, easy-to-install, easy-to-maintain, easy-to-operate system for enabling drivers and pedestrians alike to anticipate, without confusion, light changes for fuel conservation and safety purposes.